Among recent portable terminal apparatuses such as portable telephones, certain types of portable terminal apparatuses have contained therein a plurality of antennas. These portable terminal apparatuses equipped with the plural antennas are operated to perform wireless communications in such a manner that signal reception levels of antenna elements thereof are measured, and then, the wireless communications are carried out by utilizing such an antenna element having a higher signal reception level. As a result, even when a reception characteristic of one antenna element is deteriorated, since, by utilizing another antenna element having a superior reception characteristic, a portable wireless communication can be carried out, a user of a portable telephone can continuously perform comfortable portable wireless communications under better wireless communication environment.
At the present stage, a major structure of such portable terminal apparatuses is given as follows: That is, while a single antenna element having the highest reception level is employed for a portable wireless communication, the remaining antenna elements are not used for the portable wireless communication. On the other hand, current portable terminal apparatuses have been gradually provided with wireless functions using wireless communications except for portable wireless communications which are utilized in telephone conversation communications and transmissions/receptions of E-mails, while the first-mentioned wireless functions are known as, for instance, a television receiving function, a GPS (Global Positioning System) function, a wireless communication function with respect to a non-contact IC, a short distance wireless communication function with respect to an external apparatus using a short distance wireless technique (Bluetooth etc.), and the like. As a consequence, the below-mentioned portable terminal apparatuses have been so far required. That is, while the above-described remaining antenna elements are employed so as to perform such wireless communications as the television receiving function, the GPS function, the wireless communication function with respect to the non-contact IC, the short distance wireless communication function, and the like, a plurality of wireless communication functions using a plurality of antennas may be carried out at the same time.
In conventional portable terminal apparatuses, since such antenna elements which can be wireless-communicated only within frequency ranges utilized in wireless communications (namely, communicatable in narrow frequency range) have been separately provided with respect to each of these wireless communication functions, various sorts of these wireless communication functions have been carried out. However, as previously explained, in order to perform the plurality of wireless communication functions by utilizing the plurality of antenna elements at the same time, when the reception levels are low, there are some possibilities that the respective plural antennas execute various sorts of the above-explained wireless communications other than the portable wireless communications. Accordingly, these antenna elements whose reception levels are low are required to be wireless-communicatable in the respective frequency ranges utilized in these plural wireless communications (namely, these antenna elements must be operable in broad band). However, when wireless communications are carried out at the same timing by employing a plurality of broadband antenna elements, such an event may occur. That is, antenna characteristics of the respective antenna elements are deteriorated due to antenna coupling phenomena, for instance, wireless electromagnetic waves having such a frequency range which should be received by a certain antenna element are also received by another antenna element.
On the other hand, a patent publication 1 and a patent publication 2 describe wireless appliances having the below-mentioned structures: That is, while a plurality of antennas are built in these wireless appliances, signal reception levels of these plural antenna elements are measured; a portable wireless communication is carried out by utilizing a first antenna element having the highest reception level; and on the other hand, an influence caused by a second antenna element whose reception level is low can be reduced which is given to an antenna characteristic of the first antenna element. However, the second antenna element of this wireless appliance structure does not perform a portable wireless communication. As a consequence, the patent publication 1 and the patent publication 2 never solve such a problem that the antenna characteristics of the respective antenna elements are deteriorated due to the antenna coupling phenomena, which should be solved by the present invention.    Patent Publication 1: JP-A-2000-324029    Patent Publication 2: JP-A-7-221681